daddyov8

after my flat battery problems this week had chance to look at it. getting 13.37v from the alternator, when tested the battery said it was good but only 45% charged.

But after a 25 mile run as soon as its turned off its flat again. No obvious problems with either but swapped battery under warranty for a new one. All works now but probably would with new battery.

Any ideas what the correct charging v should be as the battery guy said it should be 14.4v minimum and i'm at 13.37v?

Battery is only 18mths old so have a feeling it may not be as simple as that.

Alan

The battery guy has no idea - sounds like you are OK based on that reading alone (I assume at idle?) - it was likely just the battery.

14.4v might be OK for a chevvy - it would likely hurt your 928's battery... the way things are connected in a 928 doesn't allow the wiring voltage drops that typical Detroit iron has.

When the car is off idle (1.5K RPM or more) you should have ~ 13.8v if you do (or close) you are fine. Use a DMM

BTW your alternator voltage wil change with RPM, ambient & engine (alt) temperature, loading (battery charge state and equiupment in operation) so monitor at different times under different conditions.

It likely won't hit 13.8V at hot idle

Alan